Introduction

With increasingly stringent environmental standards and a continuously rising demand for water reuse, membrane bioreactors (MBRs) have become the mainstream technology for advanced wastewater treatment and resource utilization. Membrane materials, as the core component of MBRs, directly determine the system's operational stability, treatment efficiency, and total lifecycle cost. Traditional organic membranes suffer from drawbacks such as susceptibility to fouling, short lifespan, and poor corrosion resistance, making them unsuitable for complex and harsh water conditions. Silicon carbide flat-sheet membranes, with their superior properties of ultra-corrosion resistance, high flux, long lifespan, and strong anti-fouling capabilities, provide a robust solution for MBR process upgrades and are widely used in municipal wastewater, industrial wastewater, and concentrated brine treatment.

I. Introduction to MBR Technology

1. Process Principle

MBR (Membrane Bioreactor) is a wastewater treatment process that deeply integrates biodegradation and membrane separation technologies. It replaces the secondary sedimentation tank in the traditional activated sludge process with an ultrafiltration membrane module, achieving efficient separation of sludge and water. After the wastewater enters the bioreactor, microorganisms decompose pollutants such as COD, ammonia nitrogen, and total phosphorus; the ultrafiltration membrane (pore size 0.02–0.1μm) precisely traps activated sludge, colloids, bacteria, and suspended particles, resulting in clear and sterile effluent, completely solving the problems of sludge loss and turbid effluent in traditional processes.

2. Core Features of the Process

(1) Strong treatment capacity and good effluent quality

The MBR process has a high load and higher treatment efficiency than general biological treatment reactors. The effluent quality is similar to tap water in appearance and can fully meet the requirements for reclaimed water. It is currently the technology with the best effluent quality among all wastewater treatment processes.

(2) Strong resistance to impact loads

The high sludge concentration gives MBR a strong resistance to shock loads, and it also has an extremely long sludge age, resulting in very stable effluent quality.

(3) Good ammonia nitrogen removal effect

With high sludge concentration, long sludge age, and low sludge load, it is particularly suitable for nitrification to remove ammonia nitrogen, and can remove up to 1500 mg/L of ammonia nitrogen.

(4) Less residual sludge

MBR sludge has a long sludge age, the microorganisms are in the endogenous respiration phase, the excess sludge production is low, and secondary pollution is minimal.

(5) Saves land

It does not require a secondary sedimentation tank or other filtration and purification devices. The process is simple and occupies a small area, only about 1/3 of the land area required by conventional treatment processes, making it very suitable for use in places with limited land.

(3) Automatic control, easy to equip

MBR eliminates the problems of sludge bulking and sludge loss, produces low levels of residual sludge, and can achieve fully automated control, making operation and management simpler.

II. Advantages of Silicon Carbide Flat Sheet Membranes in MBR Processes

1. Extremely corrosion resistant, suitable for extreme working conditions

Made from high-purity silicon carbide powder recrystallized and sintered at 2400℃, it is resistant to acids and alkalis in the pH range of 0–14, and can withstand corrosion from strong acids, strong alkalis, high-concentration oxidants and organic solvents. It can operate stably and without aging in harsh water conditions such as concentrated brine, chemical wastewater and landfill leachate for a long time.

2. High-throughput operation, resulting in higher processing efficiency.

The membrane surface has a water contact angle of only 10.3°, making it extremely hydrophilic. Its operating flux is stable at 60–100 LMH, which is 3–4 times that of organic membranes. For the same treatment scale, it requires less membrane area and the membrane tank occupies less space, significantly reducing civil engineering costs.

3. Strong resistance to stains, easy to clean and restore

The membrane surface is strongly negatively charged, electrostatically repelling sludge, colloids, and oil, resulting in excellent anti-fouling capabilities. Aeration and flushing delay fouling, and after fouling, high-concentration acid, alkali, and oxidant cleaning can restore 100% of the flux. The cleaning cycle is long and maintenance is simple.

4. Ultra-long lifespan and low total lifespan cost.

It has high mechanical strength, wear resistance, no risk of fiber breakage, and a service life of ≥10 years, which is 3-4 times that of organic membranes; the aeration volume is only half that of organic membranes, resulting in low energy consumption; it does not require frequent membrane replacement, significantly reducing consumable costs and downtime, and has outstanding economic benefits throughout its entire life cycle.

5. Highly compatible and easy to upgrade and modify.

It is fully compatible with existing organic MBR systems and can replace organic membranes in situ without major equipment modifications; it is suitable for complex water qualities such as high sludge concentration, high oil content, and high salinity, and is easy to upgrade and quick to show results.

III. Typical Application Cases

Case 1: A sewage treatment project in a certain township

Processing capacity: 3000 m³/d

Process scheme: Silicon carbide flat sheet membrane MBR is used to replace the traditional secondary sedimentation tank.

Application results: Stable and compliant effluent, simple operation and maintenance, effectively solving the problem of sewage discharge in rural areas.

Case 2: Upgrading Project for Concentrated Salt Wastewater from a Coal Chemical Plant

Processing capacity: 76 m³/h

Upgrade Background: The original organic membrane had a short lifespan, required frequent replacement, and was costly.

Application results: After replacing with silicon carbide flat sheet membrane, the operational stability was significantly improved, the membrane life was greatly extended, and the maintenance cost was significantly reduced.

Case 3: Wastewater Treatment Project at a Service Area

Processing capacity: 120 m³/d

Process Solution: Integrated Silicon Carbide Flat Sheet Membrane MBR Equipment

Application results: Compact footprint, automated operation, stable treatment of decentralized domestic sewage, and effluent meets standards for reuse.

Case 4: An Industrial Wastewater MBR System Project in Singapore

Processing capacity: 150 m³/d

Application effect: By replacing traditional organic membranes with silicon carbide ceramic membranes, deep treatment of industrial wastewater can be achieved in a limited space.